A radar device using an FMCW (Frequency Modulated Continuous Wave) signal receives the FMCW signal transmitted from a transmitter and reflected by an object, and multiplies the received signal and a transmitted signal transmitted at the receiving time. Here, an output signal frequency of a multiplier is determined by a time difference between the both signals, and therefore, it is possible to find a distance and a relative speed with the object, and so on.
The FMCW signal for radar use is required to have a characteristic in which a frequency changes approximately linearly relative to the time. Conventionally, a method obtaining a high linear characteristic by using an error obtained by converting a frequency of an output signal of a voltage controlled oscillator into a voltage, and thereafter comparing the voltage with a voltage signal in a triangular wave state input from external is known. Otherwise, a method in which a frequency of a reference signal of a triangular wave is multiplied by using a phase synchronization circuit of which loop bandwidth is narrow, and thereafter the multiplied signal is used as a reference signal of a phase synchronization circuit of which loop bandwidth is wide, and so on are known.
However, there are problems in the conventional methods in which it is difficult to suppress a phase noise of the voltage controlled oscillator and to maintain a linearity of the FMCW signal, and a means to correct the error is additionally required. An object of a signal generating circuit (or a signal generator) and a radar device according to an embodiment is to provide a signal generating circuit (a signal generator) and a radar device capable of obtaining a low-noise, high-frequency accuracy, and high-linearity FMCW signal.